Devil May Cry 2 walkthrough/DM13

Boss: Arius
Arius will send out a few low ranked enemies, shoot his gun, and create various spikes or weapons with his demon magic. Fighting the smaller demons are optional, for they don't effect Arius's vitality, so it would be best to aim mostly at him. There are various points throughout the battle where he'll stand there, giving you enough time to hack away at him until he teleports of summons something to attack you. Just watch where he teleports to and attack him then.